Bismarck original KTB still existing ?

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wadinga
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Re: Bismarck original KTB still existing ?

Postby wadinga » Thu Oct 12, 2017 3:23 pm

Hello Antonio,

You still seem obsessed with the irrelevant positioning of Suffolk for some reason? Have you at last realised that Wake -Walker was correct all along with his bearings and distances to both Bismarck and to Holland?

Oh well since you want to talk about Suffolk. :D

You cannot disregard D/6 and D/7 as well as you cannot disregard the same bearing of 335° similarly only partially traced by PInchin at 06:20 between Norfolk and Suffolk.


The 335T is partially traced then the D6 & D7 are of similar value because they look vaguely the same?

I surely don't have to remind you that the 06:20 bearing is a visual sighting recorded in Norfolk's Ship's Log, whereas these other two lines have no identification or provenance at all. We don't know what they are. You may choose to believe they are otherwise unrecorded D/F bearings, but to rate them as highly as a direct visual bearing would be ridiculous.

Once again I remind you I match 185T in a blind trial perfectly:

You cannot disregard now..........


and the 185° bearing between Suffolk and PoW at 05:53 at open fire.


On my map:

The distance from Suffolk to Hood at 05:53 is 50,400 yds or 25.2 miles on 185T. (0553 (B). Heavy gun flashes bearing 185°. Half a minute later Bismarck opened fire to port.)


This is 27 minutes previous to the 06:20 bearing and validates the Suffolk track between these positions. Since one bearing is from Norfolk and the last is Suffolk and Holland it suggests all three tracks are well positioned relative to one another.

I do not care at all at what distance they will end up being at the end, even if I realize with satisfaction that they are moving closer as it was obvious for me since the beginning looking at " The Plot " intentionally enlarging the battlefield as we all know now.


We are approaching the end of the meal, my friend, and you need to wake up and smell the coffee. Your collapsed, erroneous perception based on misplaced faith in diagram B and PoW's action plot is completely disproved, and the distances derived from my version of the map, not entered, but derived support Wake-Walker throughout.

All the best

wadinga
"There seems to be something wrong with our bloody ships today!"

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Antonio Bonomi
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Re: Bismarck original KTB still existing ?

Postby Antonio Bonomi » Thu Oct 12, 2017 4:21 pm

Hello everybody,

@ Wadinga,

go back on this thread and you will read my agreement with Herr Nillson to work positively on agree about a base set of bearings among us all being the base of discussion to progress further.

I ask again to you : Do you agree about the base set of bearings you can read above and see on my map ?

If YES overall on ALL of them a simple YES will be enough.

If NOT about some of them it is enough to provide a complete list with YES or NO aside every single bearing.

It is an elementary exercise I invite you and everybody else willing to cooperate here in. Please do it.

Thanks for your cooperation.

Bye Antonio :D
In order to honor a soldier, we have to tell the truth about what happened over there. The whole, hard, cold truth. And until we do that, we dishonor her and every soldier who died, who gave their life for their country. ( Courage Under Fire )

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Re: Bismarck original KTB still existing ?

Postby Antonio Bonomi » Sat Oct 14, 2017 8:48 am

Hello everybody,

@ all,

this last argument, not belonging to the Bismarck KTB events, will be moved to a dedicated thread :

The Norfolk and Suffolk tracks at Denmark Strait.


Bye Antonio :D
In order to honor a soldier, we have to tell the truth about what happened over there. The whole, hard, cold truth. And until we do that, we dishonor her and every soldier who died, who gave their life for their country. ( Courage Under Fire )

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wadinga
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Re: Bismarck original KTB still existing ?

Postby wadinga » Mon Oct 16, 2017 2:17 pm

Hello All,

Since the validity and relative accuracy of lines which may or may not be M/F D/F bearings have been mentioned, here are comments from Tovey's interim report of 30th May relating to attempts to D/F Vian's destroyers during the night before the final action.

He makes it clear that this interim report may be modified in the light of further technical information and reports from other vessels.

"D/F bearings were difficult to get and it became evident that the relative positions were not known with sufficient accuracy for a dawn approach to be practicable."

later he says:

" Between 06:00 and 07:00 D/F bearings of a series of reports from Maori enabled the relative position to be deduced with reasonable accuracy."

On the difficulty of resolving Vian's position with his own.

"It was apparent there was considerable difference in reckoning between the various ships shadowing and between them and the battlefleet: this was only to be expected with forces that had been widely separated in weather unsuitable for taking sights."

It is clear that D/F systems did not give reliable accurate bearings all the time. It is unclear whether this is M/F or H/F D/F. KG V seems to have had one of the earliest H/F systems at sea.

I look forward to seeing Cag's information.

All the best

wadinga
"There seems to be something wrong with our bloody ships today!"

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Antonio Bonomi
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Re: Bismarck original KTB still existing ?

Postby Antonio Bonomi » Mon Oct 16, 2017 3:50 pm

Hello everybody,

@ Wadinga,

obviously the visual bearings accuracy are depending from the visibility.

Obviously the R. D/F bearings are depending on the equipment precision, tolerance and accuracy.

In any case those 7 cross bearings are what we have in the most official possible way.

They will define the battlefield with a very minimum error margin anyway.

Bye Antonio :D
In order to honor a soldier, we have to tell the truth about what happened over there. The whole, hard, cold truth. And until we do that, we dishonor her and every soldier who died, who gave their life for their country. ( Courage Under Fire )

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wadinga
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Re: Bismarck original KTB still existing ?

Postby wadinga » Tue Oct 17, 2017 12:41 am

Hello Antonio,

obviously the visual bearings accuracy are depending from the visibility.


How do take a visual bearing on a thing you can't see? Visibility might affect identification, but if you can see it, you can get a bearing limited in accuracy only by your equipment.

Can we avoid muddling terms, remember RDF is radar, not direction finding. D/F is either H/F higher accuracy- and not available in Norfolk, or M/F lower accuracy. I look forward to Cag's new info on the latter.

All the best

wadinga
"There seems to be something wrong with our bloody ships today!"

dunmunro
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Re: Bismarck original KTB still existing ?

Postby dunmunro » Tue Oct 17, 2017 1:35 am

I posted this in Dec 2014:


The RN's classification method for DF results (for both MF and HF DFs:)
First-Class Bearing.—One for which the probability does not
exceed one in ten that the error will exceed 3°.
Second-Class Bearing.—As above with limit set at 4°.
Third-Class Bearing.—As above with limit set at 5°.
THE ESTIMATION OF THE PROBABLE ACCURACY OF
HIGH-FREQUENCY RADIO DIRECTION-FINDING BEARINGS*
By W. ROSS, M.A., Associate Member. (IEEE)
{The paper was first received 15th July, and in revised form 26th October, 1946.)


So an error of +/- 3 degs was considered as the best consistently possible.

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Antonio Bonomi
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Re: Bismarck original KTB still existing ?

Postby Antonio Bonomi » Tue Oct 17, 2017 5:33 am

Hello everybody,

@ Dunmunro,

I remember those data and thanks again, ... of course in this case this tolerances do apply in both directions and for all the R.D/F bearings taken, ... while for the visual it is a different story.

Anyway, ... as said those data are what we have, ... and we must play with those in this moment.

Bye Antonio :D
In order to honor a soldier, we have to tell the truth about what happened over there. The whole, hard, cold truth. And until we do that, we dishonor her and every soldier who died, who gave their life for their country. ( Courage Under Fire )

Cag
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Re: Bismarck original KTB still existing ?

Postby Cag » Tue Oct 17, 2017 3:22 pm

Hi All

Having looked at the recent posts this is probably the best place to put this info. First off I'm no expert so if anyone can add to this please feel free to do so and I recommend visiting the RN radar and communications website as it explains fully how d/f work was carried out and the science behind it.

I'm not going to go too deep into this having studied the manuals etc, there are numerous inherent causes for error, component wise, set up wise, signal frequency wise even how each signal behaved during certain parts of the day (so called night error where between dusk and dawn instead of the signal being a ground or direct wave it travels in the atmosphere and thus becomes a sky wave) some could be ironed out but the sets had to be constantly checked at the beginning of each watch.

According to a very nice man who served in the RN for many years and who used these systems by 1939 the British had a very ad hoc basis upon which the devices fitted to ships were made up from. It was typically British, conceptually good, but a bit Heath Robinson in the way devices were put together.

Each device had a specific aerial designed to be used with it. The early pre war aerials were given the prefix letter S for a d/f system and a suffix letter denoting model. Later devices had a prefix letter that denoted the aerial type and the suffix letter that denoted the frequency used. The model type was numerical.

Basically you have an aerial positioned on the fore to aft plane of the ship and an aerial formed on the port to stb plane set up so that they intersect, it is the Bellini-Tosi aerial system. Via various valve filled receivers amplifiers etc a transmitted signal could be used to produce a dc voltage to a device called a Goniometer.

I won't go into too much detail as it would bore the pants off you, but the goniometer consists of two field coils one connected to each aerial (fore to aft or port to stb) it also has a centre search coil which can be rotated in the fields of the field coils. The centre coil is attached to a pointer having three arms, the centre arm having a sliding pivot for two equal links which are symmetrically linked to the two outer arms (the centre arm is fragile and prone to warp in bad weather!).

The three legged pointer sits on a circle that is divided into two semi circles one red for port one green for stb, each semi circle is divided into 0°-180° denoting bow to stern. There is also a gyro compass with its take off from the bridge either close by or attached around the outside of the two semi circles, so that a red or green bearing or a compass bearing can be noted.

The operator uses a handle to turn the three armed pointer to find a signal strength, he then locks one of the outside arms to this point and searches for the other side of the signal strength and hopefully the central arm gives a bearing. This is the zero or null and the reciprocal bearing is the direction of the transmitted signal.

When the system is set up correction curves are produced for each ship that allow the bearing to be corrected for various reasons and which can be applied. The aerials had to be set up and in sinc with the goniometer and tested to see if false nulls were created by various metal parts of the superstructure. If this was the case the ship would have to be turned until the signal was out of this false null area. If a device had no such false nulls it was termed uniform as all signals were amplified without bias.

All the Goniometer could do was work when the signal was transmitted, later huff duff could get a bearing in seconds, the ones at the DS would take minutes which is why the d/f bearing is always later than the signal, time taken for receipt and then the operator to estimate a line of bearing LOB. Three LOB lines would result hopefully in a search triangle.

Hood in 1939 had an FH2 fitted, F denoting fixed frame aerial and H for high frequency 670khz to 20mhz and model no2. This can be seen at the top of the mainmast and was two diamond shaped frames one in the fore to aft plane one in the port to stb.

She also had an LM1, L denoting Loop or wire aerial and M for medium frequency 60-670khz. This was in between her funnels, a square fore to aft aerial attached by each funnel, and a triangular port to stb mounted between two arms and the top attaching to a stay rigged between the mainmast and foremast. Unfortunately when she had her 279M RDF aerial fitted she lost her H/F capability which is no doubt why PoW was delegated the d/f role.

PoW had an FC2 unit F again for fixed frame and C for common aerial for H/F and M/F reception 60khz-20mhz and version 2. It can be seen below her after mast starfish again a diamond shaped aerial.

Suffolk had LM1 like Hood and Norfolk was the oldest of the bunch with a pre war SD unit also a wire loop aerial. I'm not sure where these were placed being loop aerials as usually they were between funnels etc but on a three funnel ship? Here is where an expert comes into play.

To be fair the systems could only give an estimate of a line of bearing, not distance, that was the domain of RDF, but it was useful, it gave a good idea of direction and if multiple transmissions received an idea of direction of travel. But even if you had a fully uniform aerial, with a good direct ground wave in the best of conditions with a top operator the expected error was 3 to 3.5° on each bearing, and this is for FH and FC models. The greater the distance the wider the arc this error would produce.

I hope this helps and was understandable, as I say visit the RN museum of radar and communications website as they have reams of info, I know how the orders for how they were to set up the systems etc but to reproduce here I'm afraid you'd be asleep before I was finished!

Best wishes
Cag.

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Re: Bismarck original KTB still existing ?

Postby wadinga » Tue Oct 17, 2017 8:20 pm

Hello Cag,

Excellent information :clap: :clap: :clap:

There is one thing to be careful of:

the ones at the DS would take minutes which is why the d/f bearing is always later than the signal, time taken for receipt and then the operator to estimate a line of bearing LOB. Three LOB lines would result hopefully in a search triangle.


The operator can only get an estimate during the transmission by trying to establish null signal. The shorter the transmission the less chance and hence accuracy.

Three LOBs: This is a technique for a single ship on a non-moving radio transmitter eg shore station. If you get three LOB along your own track (Baseline) over a period of time, on a fixed transmitter, you can confirm or if in error modify your track. If the transmitter is moving in the meantime, like Suffolk is, three bearings cannot give you a position for her. Antonio has already attempted something similar, only he tried to use two entirely different ships on an unknown baseline, to explain a unexplained "position" for Suffolk, in the early hours of the 24th.

The four arrows on the PoW action plan represent several D/Fs on Suffolk in the earliest hours, nothing shown later, but since she moves between transmissions they are just a series of non-parallel, non-converging lines (+ or - 3 degrees thanks Duncan) which tell you nothing more than she was heading SW fast, which is obvious from her reports. No way can they give you a position for the transmitter.

All the best

wadinga
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Antonio Bonomi
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Re: Bismarck original KTB still existing ?

Postby Antonio Bonomi » Wed Oct 18, 2017 6:47 am

Hello everybody,

@ CAG,

many thanks for having provided us more information regarding R.D/F transmission and equipment, ... but it is not a new for us since we already discussed about it time go, ... non one assumed it was a defect free equipment, ... and a tolerance was assumed.

Nothing changes, ... those bearings is what we have, either visual or R.D/F taken, ... and we have to use them.

@ Wadinga,

referencing above, ... assuming tolerances just like for everything else, ... like speed and distances, ... that is what we have and we will use, ... and you must consider also that a tolerance in one taken direction is compensated by a similar tolerance in the opposite direction and so on for cross bearings, ... so it is not an easy mathematical exercise to evaluate the overall estimate, ... and mostly it is useless in this case because at the end, ... bottom line, ... that is what we have and must use.

Bye Antonio :D
In order to honor a soldier, we have to tell the truth about what happened over there. The whole, hard, cold truth. And until we do that, we dishonor her and every soldier who died, who gave their life for their country. ( Courage Under Fire )

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wadinga
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Re: Bismarck original KTB still existing ?

Postby wadinga » Wed Oct 18, 2017 9:06 am

Hello Antonio,

I'm sorry to be pedantic, but this is very important.

R.D/F taken


is incorrect usage. For instance where on Suffolk's strategical map is has "RDF bearings" they are radar bearings with a higher level of bearing accuracy and a range. Where on PoW's action plot it shows arrows, these are D/F bearings with a lower degree of azimuth accuracy and no range whatsoever.

It is not so long ago you were claiming the "positions" shown for Suffolk by triangles were the result of single D/F line of bearing from Norfolk and very recently your most supportive supporter was claiming unidentified lines which might or might not be D/F LOB were as valid and precise as a visual sighting. Thus a reminder of the limitations of 1941 D/F and the installations present at DS from CAG and sourced from an historic user is most useful.

All the best

wadinga
"There seems to be something wrong with our bloody ships today!"

Cag
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Re: Bismarck original KTB still existing ?

Postby Cag » Wed Oct 18, 2017 9:34 am

Hi All

Hi Wadinga,

Thanks I didnt want to get too technical with it only the relevant info different ship fitments, error etc, yes I agree, sorry maybe I worded it wrong, the shorter the signal the harder it would be, plus signal strength night effect etc, it would still take minutes for the operator to estimate a bearing as he would also have to apply the relevant correction curve data, ship movement, compass check etc etc.

Yes again maybe it was not obvious sorry three LOB would be on the same signal not three different ones, despite the errors in the three LOB they would hopefully provide a search triangle in which the transmitter that had signalled was located. For three independant signals ie if Norfolk and Suffolk were both on a relatively similar course, and doing a similar speed, and the d/f bearings were very accurate, then the bearings in theory should not converge but remain fairly parallel and the LOB show, at least, a movement direction but no distance.

Hi Dunmunro

Missed your post, sorry, but at least my figures match yours at 3-3.5° error, the huff duff sets still had an error of 2-2.5° according to later records but at least with rotatable aerials etc it only took matter of a minute to get an LOB. It is amazing to see on the equipment lists the various receivers tuners amplifiers magnifiers heterodyne units used as well as goniometers, even the lists of valves used! A refit and upgrade could just mean newer better valves!

Hi Antonio,

That's ok, it was for my own interest and hopefully it may help others who are interested in the different fitments in different ships. There was a lot of discussion about d/f and I needed to understand the science behind it. I think those shown on the plot were just to show the timings etc of the d/f positions and the bearings. In reality it shows the idea of the movement of Suffolk despite being out of sight but I guess for us it also shows the failings of d/f too.

Best wishes
Cag.


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